The Topeak Redlite Race Rear Light ensures you remain highly visible at all times, with a compact and powerful design you are guaranteed full visibility to passers-by for up to 100 hours of use. With the ability to choose between blinking or constant modes you can set the rear light to the most suitable setting for the current environment, the mount design attaches to the post or seatstay securely. Topeak Redlite Race Features Lamp: 2 Super Bright Red LED’s Battery: CR2032 x2 (included) Burn Time: (approx.) 70hrs / 100 hrs Blinking or constant functions 7x3.6x3.8cm 37.6g "